1. Field of the Invention
The present invention relates to an electron device utilized in a cold-cathode device functioning as an emitter of electron beam in a micro vacuum tube, a light-emitting device array, etc.
2. Related Background Art
Conventional semiconductor devices had such drawbacks that electron mobility is as low as 1/1000 times that in vacuum and that reliability is low against radiation. On the other hand, conventional vacuum tubes had no such drawbacks. It has thus been being considered that ICs having the performance of the conventional vacuum tubes could be produced by fabricating the micro vacuum tube using the micromachining techniques fostered in the field of Si semiconductor devices. Accordingly, the micro vacuum tube overcoming the drawbacks of the conventional semiconductor devices has been vigorously studied and developed effectively using the fabrication technology of Si semiconductor devices.
Studied in connection with such a trend is an emitter of electron beam used in the micro vacuum tube, the light-emitting device array, etc. The conventional vacuum tubes, however, had a drawback of needing a long standby time of several minutes between start of operation and a state of being ready for use. Overcoming it, electron devices such as the micro vacuum tube considerably shortened the standby time by such an arrangement that the tip of an emitter portion is micromachined like a very acute needle by the fabrication technology of Si semiconductor devices so that electrons can be emitted by the field emission.
Also, it comes to recent attention that diamond is used as a material for the electron devices. Diamond has the thermal conductivity of 20 W/cm.multidot.K, which is maximum among other materials for the electron devices and which is 10 or more times larger than that of Si. Since diamond is thus excellent in heat radiation for a large current density, electron devices operable at high temperatures can be produced using diamond as a constituent material.
Further, diamond is an insulator in an undoped state, which has a high dielectric strength, a small dielectric constant of 5.5, and a high breakdown voltage of 5.times.10.sup.6 V/cm. Thus, diamond is a potential material for electron devices for high power used in the high-frequency region.
To produce low-resistance diamond, Geis et al. at MIT formed an n-type diamond semiconductor by implantation of carbon.
This prior art technology is described in detail, for example, in "Appl. Phys. Lett., vol. 41, no. 10, pp 950-952, November 1982."